Practical question: How are media containing antibiotics properly disposed of after genetic engineering work has been completed?

The increased release of antibiotics from agricultural and research facilities into the environment is leading to the emergence of multi-resistant microorganisms, which can pose serious problems in the treatment of infectious diseases in humans. Appropriate organizational measures must therefore be taken to ensure that laboratory waste containing antibiotics (especially liquids) is only disposed of after appropriate pretreatment or inactivation. In genetic engineering work, antibiotic-containing culture media are used for the selection of recombinant microorganisms or as a preventative measure to prevent microbial contamination. After completion of the work, the genetically modified organisms (GMOs) used are often inactivated using thermal processes such as autoclaving. Heating the GMOs in the autoclave destroys their biological activity, so that from the perspective of genetic engineering law, the waste can generally be safely disposed of after autoclaving. However, what about the heat resistance of the antibiotics used, and are they truly inactive after autoclaving? In a very informative publication by Meyer et al. ( Journal of ABSA International 2017, 22; 164-167), the data on the heat resistance of frequently used antibiotics were summarized. According to this publication, members of the ß-lactam antibiotic group (penicillin, ampicillin, carbenicillin), for example, are reliably inactivated by autoclaving (15 min, 121°C) of appropriate culture media. The same applies to members of the aminoglycoside group (e.g. geneticin, gentamycin or streptomycin). Kanamycin occupies a special position in this group, as it is only completely inactivated in an environment with a very low pH value during autoclaving. The antibiotics erythromycin and puromycin, which are frequently used in genetic engineering laboratories, are also no longer active after autoclaving. It is important to note that the information provided refers only to antibiotic-containing media and not to the corresponding stock solutions of the antibiotics.
Heat-stable antibiotics include blasticidin, chloramphenicol, zeocin, and ciprofloxacin. Autoclaving under standard conditions does not completely inactivate the antibiotic activity. Culture media containing these or other heat-stable antibiotics must be collected after autoclaving in accordance with the requirements of hazardous substances legislation and disposed of as hazardous waste. The same applies to untreated, antibiotic-containing media from experiments with biological safety measures according to Sections 7 and 8 of the GenTSV (Genetic Safety Regulations) at safety level 1, for which inactivation of the GMO in the autoclave is not mandatory.